<p>This paper discusses the nonlinear formability problem and studies the semi-global sampled-data formation control problem for a class of nonlinear multi-agent systems. There is no any linear growth condition for nonlinearity of the agents, which brings the challenges to the nonlinear analysis and synthesis. Based on the steady-state analysis for closed-loop system, the sufficient and necessary condition that guarantees the exact formability is proposed. Then, the formation condition under sampled-data mechanism is studied and given. Using the proposed formation condition, the formation control of nonlinear multi-agent systems is achieved by synthesizing a distributed sampled-data formation control law. In the end, the simulations are carried out to show the correctness of the proposed formation condition.</p>